1. Field of the Invention
The present invention relates to a method and a measuring apparatus for continuously measuring the resistance of a track to transverse displacement while the track is oscillated in a horizontal plane and in a transverse direction and to a dynamic track stabilizer incorporating such a method and apparatus.
2. Description of the Prior Art
U.S. Pat. No. 4,643,101 discloses a mobile track leveling, lining and tamping machine to which a dynamic track stabilizer is coupled. The track stabilizer may be a self-propelled machine which may be operated independently or in connection with other track working machines when uncoupled. As is known, dynamic track stabilization considerably improves the stability and particularly the resistance of the track to transverse displacement after tamping, which causes the ballast bed to become relatively loose. Dynamic track stabilization artificially simulates in a single operation what train traffic over a long period of time produces: settling and consolidation of the ballast to provide a firm support for the track at a desired position. This is achieved by frictionally gripping the rails of the track by rollers adjustably mounted on a track stabilization unit and imparting oscillations to the gripped track which extend in a horizontal plane in a transverse direction while at the same time applying a vertical load to the track, thus simulating the force a passing train applies to the track. The dynamic track stabilization "rubs" the track into the ballast, causing the ballast to be consolidated and the track to be settled at a desired level if the operation is controlled by a track level reference system. The result is not only a durable and uniformly elastic ballast bed but also an increased resistance to a transverse displacement of the track, which is a function of the friction between the track ties and the ballast.
The quality of the ballast bed consolidation may be deduced from the magnitude of the resistance of the track to transverse displacement (QVW), which determines the lateral stability of the track. The measurement of this lateral resistance has been made independently of the dynamic track stabilization or other track work. For example, an article by Gyula Sari, entitled "The Influence of the Dynamic Track Stabilizer on Track Geometry," in Transport International, No. 1, June 1981, pp. 3-6, describes such a measurement made at individual ties of a track. In this measurement operation, the rail fasteners are first removed at the tie where the measurement is made, the ballast next to one end of the tie is removed without disturbing the remaining ballast surrounding the tie, and a measuring device consisting of a hydraulic cylinder is attached to the tie end to displace the tie in a transverse direction by the application of a steadily increasing hydraulic pressure. Measurement of the displacement enables the lateral resistance to be determined. This measuring operation requires a substantial amount of work and also can be done only in spot checks.
Finally, U.S. Pat. No. 5,127,333 discloses a dynamic track stabilizer with a device for measuring the amplitudes of the horizontal oscillations, from which the resistance of the track to transverse displacement (QVW) may be deduced.